Propylene polymer composites having improved melt strength
AssigneeEquistar Chemicals, LP
InventorsSameer D. Mehta, Manivakkam J. Shankernarayanan, Harilaos Mavridis
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Abstract
Propylene polymer composites containing modified clays and compatibilizing agents, more specifically hydrogenated tallow modified montmorillonite and maleic anhydride grafted propylene polymers, are provided. Concentrates or masterbatches used to prepare the composites are also described. The improved composites of the invention exhibit increased melt strength compared to the base resin and to composites similarly formulated using other types of modified clays. Moreover, the improved results are achievable at lower compatibilizer levels and lower ratios of compatibilizer to clay than has heretofore been considered practical.
Claims15
A thermoplastic resin composite having improved melt strength comprising:
- (a) 76 to 99 weight percent, based on the total composition, of a thermoplastic propylene copolymer base resin selected from the group consisting of random propylene-ethylene copolymer and two-phase compositions comprising a continuous phase of highly isotactic polypropylene homopolymer and a dispersed phase of rubber-like Ipropylene-ethylene copolymer;
- (b) 0.5 to 12 weight percent of an organically modified clay consisting of a smectite clay that has been ion-exchanged and intercalated with a quaternary ammonium compound of the formula:
- (R)n(CH3)mN+Cl−
- where R represents a hydrogenated tallow moiety, n is 1 to 4, m is 0 to 3 with the proviso that n+m=4;
- and
- (c) 0.5 to 12 weight percent of a propylene copolymer compatibilizing agent having a melt flow rate from 40 to 400 g/10 min. and obtained by grafting 0.2 to 2.5 weight percent maleic anhydride and 97.5 to 99.8 weight percent propylene-ethylene copolymer, the weight ratio of (b):(c) ranging from 1:5 to 1:0.1.
A concentrate useful for the preparation of composites having improved melt strength comprising 20 to 60 weight percent propylene polymer carrier resin selected from the group consisting of propylene homopolymer, propylene copolymer and mixtures thereof and 40 to 80 weight percent additives comprising an organically modified clay consisting of a smectite clay that has been ion-exchanged and intercalated with a quaternary ammonium compound of the formula:
- (R)n(CH3)mN+Cl−
- where R represents a hydrogenated tallow moiety, n is 1 to 4, m is 0 to 3 with the proviso that n+m=4 and a propylene polymer compatibilizing agent obtained by copolymerizing or grafting 0.1 to 8 weight percent ethylenically unsaturated carboxylic acid or derivative monomer and 95 to 99.9 weight percent propylene, the weight ratio of organically modified clay to compatibilizng agent ranging from 1:5 to 1:0.1.
Dependencies are inferred from the claim text.